Methods and systems for providing enhanced position location in wireless communications

Abstract

Embodiments disclosed herein relate to methods and systems for providing improved position-location (e.g., time-of-arrival) measurement and enhanced position location in wireless communication systems. In an embodiment, an access point may replace information (e.g., data) transmission by a “known” transmission (or “reference transmission”) at a predetermined time known to access terminals in the corresponding sectors. The access terminals may use the received reference transmission to perform a position-location measurement, and report back the measured information. The access point may also send a reference transmission on demand, e.g., in response to a request from an access terminal in need for a location-based service.

1. A method for wireless communications, comprising:
 receiving a pilot signal and a reference signal in a time slot, wherein the reference signal is received in lieu of at least a portion of traffic data over a traffic channel, the reference signal comprising a sequence of symbols known to a receiver; and 
 performing a position-location measurement based on the pilot signal and the reference signal. 
 
     
     
       2. The method of  claim 1 , wherein the time slot includes a pilot channel time-division-multiplexed with the traffic channel, the pilot channel carrying the pilot signal and the traffic channel carrying the reference signal. 
     
     
       3. The method of  claim 1 , further comprising identifying the reference signal carried by the traffic channel. 
     
     
       4. The method of  claim 1 , wherein the pilot signal and the reference signal are code-division-multiplexed in the time slot. 
     
     
       5. The method of  claim 1 , further comprising searching for the pilot signal. 
     
     
       6. The method of  claim 5 , wherein the searching for the pilot signal is based on the received reference signal. 
     
     
       7. The method of  claim 1 , wherein the reference signal is substantially identical to the pilot signal. 
     
     
       8. An apparatus for wireless communications, comprising:
 means for receiving a time slot having a pilot signal and a reference signal, wherein the reference signal is received in lieu of at least a portion of traffic data over a traffic channel; and 
 means for performing a position-location measurement based on the pilot signal and the reference signal. 
 
     
     
       9. The apparatus of  claim 8 , further comprising means for searching for the pilot signal. 
     
     
       10. A method for wireless communications, comprising:
 receiving a pilot signal and a portion of a control channel, wherein information received over the portion of the control channel is known at a receiver prior to being received; and 
 performing a position-location measurement based on the pilot signal and the portion of the control channel. 
 
     
     
       11. The method of  claim 10 , wherein the portion of the control channel includes a preamble. 
     
     
       12. A method for wireless communications, the method comprising steps of:
 receiving a time slot comprising a pilot channel and at least one other channel, wherein the pilot channel comprises a pilot signal, and the at least one other channel comprises a reference signal having information which is known at a receiver prior to being received; and 
 performing a position-location measurement based at least on the reference signal. 
 
     
     
       13. The method of  claim 12 , wherein the step of performing comprises carrying out a time-of-arrival (TOA) measurement based at least on the reference signal. 
     
     
       14. The method of  claim 13 , wherein the step of carrying out is based in part on the pilot signal. 
     
     
       15. The method of  claim 12 , further comprising sending a request for the reference signal. 
     
     
       16. The method of  claim 15 , wherein:
 the step of receiving is performed in response to the step of sending; 
 the steps of receiving, performing, and sending are performed at an access terminal; and 
 the step of sending comprises transmitting to an access point. 
 
     
     
       17. The method of  claim 16 , wherein the step of transmitting is performed in accordance with a code division multiple access (CDMA) standard. 
     
     
       18. The method of  claim 16 , wherein the access terminal is not configured to decode the reference signal. 
     
     
       19. The method of  claim 12 , wherein the at least one other channel comprises a traffic channel, and the step of receiving comprises receiving the reference signal on the traffic channel. 
     
     
       20. The method of  claim 12 , wherein the step of receiving is performed according to a predetermined schedule. 
     
     
       21. The method of  claim 12 , wherein the step of receiving is performed on a periodic basis. 
     
     
       22. The method of  claim 12 , wherein the at least one other channel comprises a traffic channel, and the step of receiving comprises receiving the reference signal on the traffic channel when the traffic channel is idle. 
     
     
       23. The method of  claim 12 , wherein the at least one other channel comprises a control channel, and the step of receiving comprises receiving the reference signal on the control channel. 
     
     
       24. A wireless device comprising:
 at least one receiver; 
 at least one transmitter; and 
 at least one controller coupled to the at least one receiver and to the at least one transmitter, wherein the at least one controller is configured to perform steps comprising:
 receiving a time slot comprising a pilot channel and at least one other channel, wherein the pilot channel comprises a pilot signal, and the at least one other channel comprises a reference signal having information which is known at the receiver prior to being received; and 
 performing a position-location measurement based at least on the reference signal. 
 
 
     
     
       25. The wireless device of  claim 24 , wherein the controller is further configured to execute the step of performing by carrying out a time-of-arrival (TOA) measurement based at least on the reference signal. 
     
     
       26. The wireless device of  claim 25 , wherein the step of carrying out is based in part on the pilot signal. 
     
     
       27. The wireless device of  claim 24 , wherein the controller is further configured to send a request for the reference signal. 
     
     
       28. The wireless device of  claim 24 , wherein the wireless device comprises an access terminal, and the controller is further configured to send to an access point a request for the reference signal. 
     
     
       29. The wireless device of  claim 28 , wherein the controller is further configured to perform the step of sending in accordance with a code division multiple access (CDMA) standard. 
     
     
       30. The wireless device of  claim 28 , wherein the wireless device is not configured to decode the reference signal. 
     
     
       31. The wireless device of  claim 24 , wherein the at least one other channel comprises a traffic channel, and the step of receiving comprises receiving the reference signal on the traffic channel. 
     
     
       32. The wireless device of  claim 24 , wherein the controller is configured to execute the step of receiving according to a predetermined schedule. 
     
     
       33. The wireless device of  claim 24 , wherein the controller is configured to execute the step of receiving on a periodic basis. 
     
     
       34. The wireless device of  claim 24 , wherein the at least one other channel comprises a traffic channel, and the step of receiving comprises receiving the reference signal on the traffic channel when the traffic channel is idle. 
     
     
       35. The wireless device of  claim 24 , wherein the at least one other channel comprises a control channel, and the step of receiving comprises receiving the reference signal on the control channel. 
     
     
       36. A computer program product, comprising:
 computer-readable medium comprising:
 code to cause a computer to communicate wirelessly, comprising: 
 code to receive a time slot comprising a pilot channel and at least one other channel, wherein the pilot channel comprises a pilot signal, and the at least one other channel comprises a reference signal having information which is known at a receiver prior to being received; and 
 code to perform a position-location measurement based at least on the reference signal. 
 
 
     
     
       37. The computer program product method of  claim 36 , wherein the code to perform comprises code to carry out a time-of-arrival (TOA) measurement based at least on the reference signal. 
     
     
       38. A wireless device comprising:
 means for receiving; 
 means for transmitting; and 
 means for processing coupled to the means for receiving and to the means for transmitting, wherein the means for processing is configured to perform steps comprising:
 receiving a time slot comprising a pilot channel and at least one other channel, wherein the pilot channel comprises a pilot signal, and the at least one other channel comprises a reference signal having information which is known at a receiver prior to being received; and 
 performing a position-location measurement based at least on the reference signal.